Concept for a fractional energy barrier tunneling junction

Abstract

In general, the tunnel current in field emission tunneling junctions is determined by the barrier height under an applied electric field. Introducing an alternative way to modulate the tunnel current other than tuning the barrier height is important for further improving the related device performance. In this work, we propose a concept of a fractional energy barrier tunneling junction that exploits the field enhancement at the tip structure to modulate the shape of the barrier not just its height to tune the tunnel current. Compared with a classical triangular energy barrier, we find that the fractional energy barrier creates a thinner or thicker barrier width for electrons holes depending on the voltage bias, which allows us to enhance or suppress electron or hole currents by several orders of magnitude. By optimizing the barrier layer thickness for a given barrier height, we were able to make 99% of the total tunnel current to be from electrons only. This can greatly enhance the emission efficiency that is useful for application of tunneling cathode. We note that the concept proposed in this study can be extended to other field-injecting hot carrier devices.